Bradykinin storm and Cytokine storm

Subject: Science and tech

Context:

A supercomputer’s recent analysis of data on the contents collected earlier from the lungs of patients with the COVID-19 infection has showed that a phenomenon called a ‘bradykinin storm’

Concept:

• Scientists are still trying to understand the causes for the rapid deterioration in some patients with COVID-19.
• While the cytokine storm is able to explain certain aspects of what goes wrong, doctors treating patients are often foxed by the severity with which the SARS-CoV-2 virus seems to affect some people.

Bradykinin storm

• Bradykinin is a compound that is related to pain sensation and lowering blood pressure in the human body.
• According to the researchers, SARS-CoV-2 uses a human enzyme called ACE2 like a ‘Trojan Horse’ to sneak into the cells of its host.
• ACE2 lowers blood pressure in the human body and works against another enzyme known as ACE (which has the opposite effect).
• The analyses further found that the virus caused the levels of ACE to fall in the lungs, and consequently pushed up the levels of ACE2.
• As a chain reaction, this increases the levels of the molecule bradykinin in the cells, causing a bradykinin storm. Bradykinin causes the blood vessels to expand and become leaky, leading to swelling of the surrounding tissue.
• In addition, the levels of a substance called hyaluronic acid, which can absorb more than 1,000 times its own weight in water to form a hydrogel, increased.
• In effect, the bradykinin storm-induced leakage of fluid into the lungs combined with the excess hyaluronic acid would likely result in a Jello-like substance that is preventing oxygen uptake and carbon dioxide in the lungs of severely affected COVID-19 patients.

Cytokine storm

• An immune reaction triggered by the body to fight an infection is known as a cytokine storm when it turns severe.
• The body releases too many cytokines, proteins that are involved in immunomodulation, into the blood too quickly.
• While normally they regulate immune responses, in this case they cause harm and can even cause death.
• Experts have noticed a violent cytokine storm in several individuals who are critical with COVID infection.
• These cytokines dilate blood vessels, increase the temperature and heartbeat, besides throwing blood clots in the system, and suppressing oxygen utilisation.
• If the cytokine flow is high and continues without cessation, the body’s own immune response will lead to hypoxia, insufficient oxygen to the body, multi organ failure and death. Experts say it is not the virus that kills; rather, the cytokine storm.